Sift 3 tablespoons of unsweetened cacao powder through a fine-mesh strainer into a small bowl to remove any lumps.

Add about 1/4 cup of hot water to the sifted cacao powder and whisk until you form a smooth, thin paste with no clumps.

Pour 2 cups of whole milk into a small saucepan and heat over medium heat until gentle steam appears and small bubbles form around the edges, about 150-160°F.

Stir in 2 tablespoons of honey or maple syrup and 1/4 teaspoon of vanilla extract into the warm milk until fully dissolved, about 30 seconds.

Slowly pour about 1/2 cup of the hot milk into the cacao paste while whisking constantly to temper and smooth the mixture.

Return the cacao mixture to the saucepan with the remaining milk and whisk steadily until fully combined and slightly frothy, about 30 seconds.

Sprinkle a pinch of sea salt and 1/8 teaspoon of ground cinnamon, if using, into the drink and whisk for an additional 10 seconds to incorporate.

Whisk vigorously for a final 20 seconds to create a light foam layer, then pour the cacao drink evenly into two serving mugs and serve immediately.